This invention relates generally to computer simulation results enhancement, and more particularly to the enhancement of partial simulation results by the post-simulation processing of a partial results data base using elemental characteristics available from the modeling subsystem upon which the partial simulation was based.
Simulation systems are widely used in various product development environments, including design and manufacturing engineering. They are also used in a variety of engineering disciplines, including electrical and mechanical engineering. Simulation software is traditionally equipped with a modeling subsystem adapted to a particular engineering discipline.
An electrical engineer might, by defining a circuit as a combination of elemental models that describe, in turn, voltage and current characteristics of the element, construct a model of a circuit to be simulated. The engineer might then designate the values of constants within the system, e.g. the value of a resistor or capacitor, and specify the initial conditions of desired system stimuli.
By executing a simulation program that accesses this circuit model, the engineer may determine, by viewing or plotting tabulated data or waveforms, the circuit's response to such stimuli, thereby predicting the operational behavior of the circuit. Thus, the costly, iterative trial and error process inherent in circuit design may be expedited and cost reduced. If it is discovered, during viewing or plotting, that a particular nodal voltage is not within permissible parameters or is otherwise undesirable, the circuit may be redefined by adding or changing a device type or value, and the simulation may be repeated. A circuit's theoretical operation thus may be tested and its operational parameters proved or improved, without resort to what is referred to as breadboarding.
Simulation software traditionally produces only partial simulation results, e.g. nodal voltages as a function of time. Memory capacity, turnaround time and budget traditionally constrain the extent to which simulation results include, for example, the instantaneous current flowing in, or the instantaneous power dissipated by, a circuit element. A simulator capable of producing what may be thought of as an interim results data base that enables the derivation, from the modeling subsystem, of multiple variable waveform characteristics is described in my co-pending application, Ser. No. 06/918,383, entitled "System Performance Simulator", filed Oct. 14, 1986, as well as in my co-pending application (a continuation thereof), Ser. No. 07/264,383, entitled "System Performance Simulator", filed Oct. 31, 1988.
Post-simulation processing of such an interim results data base, using a modeling subsystem that is capable of fully characterizing a circuit element to include, e.g. current (I) as a function of voltage (V) based upon the element's V-I attributes, would allow the production of more complete, and thus utility enhanced, simulation results.
Equally importantly, co-simulation processing of such an interim data base would render the simulation more interactive with, and responsive to, to the user. For example, because they are not essential to the completion of a simulation run, particular device parameters may be exceeded without the indication, if at all, until after the simulation has fully executed. Thus, it is desirable for a simulation system to allow the user selectively to augment an elemental model, e.g. by inputting specific parameters such as P.sub.d,max of a resistor or V.sub.ce,max of a transistor, and to determine, during the simulation run, whether such parameters are exceeded. Further, the ability to control a simulation while it is executing, e.g. by conditionally halting or branching, would save significant execution time. It also would ensure that the simulation comprehensively predicts the operation of the circuit modeled by the user.
The present invention discloses a software system and method whereby partial simulation results may be enhanced by software associated with the partial results data base and with the modeling subsystem to produce simulation completion results It also permits a user to specify parameters of interest to the particular application, thereby to control the simulation run. The enhancement software of the present invention provides unprecedented performance in interactive simulation.
A principal object of the invention is to provide simulation results enhancement software that fully exploits the elemental characterization capability of the modeling subsystem part of a simulation system.
An important object of the invention is to provide a method of enhancing a partial simulation results data base by post-simulation processing of the same, using the elemental modeling subsystem.
Another principal object of the invention is to provide simulation results enhancement software that permits user-inputted, expression-defined events to control the simulation.
A further object of the invention is to provide such software and such a method that are compatible with existing modeling subsystems and simulation systems.
According to a preferred embodiment of the invention, results enhancement software is operatively associated with a partial simulation results data base, produced by simulation software, and the modeling subsystem of such simulation software. The simulation completion results data base produced thereby represents all pertinent circuit attributes within the purview of the modeling subsystem, rather than simply those attributes needed to execute a simulation. Importantly, attributes of a device that are deemed pertinent may be added by the engineer to an elemental model, referred to herein as a template. Thus, the central library of elemental models may still be maintained by, e.g. a central data base group, while the templates may be customized, via an expression-oriented interface, to a particular user's application. The preferred embodiment is illustrated in the context of analog circuit design, as providing a data base representation of voltage, current and power as a function of time.
By the preferred embodiment or method of practicing the invention, the advantage of lower cost simulation is combined with utility enhanced results that include complete circuit characterization.
These and other advantages and features of the invention will become more fully apparent when the detailed description below is read with reference to the accompanying drawings.